Test suite covering:
- metrics.py: WER computation, timestamp accuracy, text normalization
- config.py: defaults, .en model detection, policy aliases, from_namespace
- timed_objects.py: ASRToken, Silence, Transcript, Segment, FrontData
- hypothesis_buffer.py: insert, flush, LCP matching, pop_committed
- silence_handling.py: state machine, double-counting regression test
- audio_processor.py: async pipeline with MockOnlineProcessor
All tests run in ~1.3s without downloading any ASR models.
Add pytest and pytest-asyncio as optional test dependencies.
Update .gitignore to allow tests/ directory.
